Setting ArrayField to null or []

Question

files = fields.ArrayField(models.UUIDField(null=True), blank=True,
                              default=None)

So I have this line in my model, the task is to keep array of UUIDs of files in the field "files", but i still get an error

The array field was imported from postgres fields like so

from django.contrib.postgres import fields

and models was imported

from django.db import models

Here is the error while executing python manage.py migrate after python manage.py makemigrations

File "/usr/local/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 447, in add_field
    self.execute(sql, params)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 137, in execute
    cursor.execute(sql, params)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python3.7/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/usr/local/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: column "files" contains null values

Update: The thing is the field is should be optional, so if the client decides to upload a photo or any files related to this model later this should be done

AKX · Accepted Answer · 2020-04-14 12:05:11Z

8

I think you want an array of non-nullable UUIDs:

files = fields.ArrayField(models.UUIDField(), blank=True)

That is, the array itself may not contain nulls.

To initialize the field to an empty list, pass in a factory function (never a mutable object!); list(), as you know, returns an empty list.

files = fields.ArrayField(models.UUIDField(), blank=True, default=list)

If you do need to distinguish between NULL files and no files,

files = fields.ArrayField(models.UUIDField(), blank=True, null=True)

will do the trick.

(That said, are these files represented by other models? If so, you may really be looking for a ManyToManyField; this sort of array field has no referential integrity guarantees!)

edited Apr 14, 2020 at 12:05

answered Apr 14, 2020 at 12:00

AKX

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5 Comments

Jay Over a year ago

Nope the thing is the array is only related and represented in this model, and won't be used in anything else. I've updated the question

AKX Over a year ago

Unless you need to distinguish between "the user has not chosen anything yet" (i.e. NULL or None) and "the user has chosen no files" (i.e. []), this will work for the updated usecase.

AKX Over a year ago

Added another variation anyway.

AKX Over a year ago

Did you re-migrate? Are you sure you're not explicitly assigning None to the field if it's not null=True?

Jay Over a year ago

Fixed the problem by deleting prev migrations on the same field and then migrating again. Thanks for help!

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